Gps position fix lost

[Beauradford]

I have a E120 connected to a new raystar 125 GPS antenna. The previous GPS antenna, a Raystar 120 of 2006 vintage,began to fail.The reoccurring problem is all is ok and then the alarm goes accompanied by an onscreen message stating the position fix is lost.I can observe the signal failure on the GPS status page.One moment the unit is fine,tracking 8 or 9 sats with a HDOP of 1.0,a minute later only tracking 1 or 2 sats and HDOP of 9+.As I stated all other functions seem normal,voltage is ok,boat stable at the dock.

My guess is the new 125 gps antenna is defective or a loose connection.The antenna is a hockey puck mounted on top of the radar arch.There is a radar dome partially obstructing the straight up view but this did not cause a problem for years.

[Mark - Raymarine - Moderator]

Hello Beauradford,
The RS125 is actually wired slightly different than that of the RS120.
The RS120 only used three of the five antenna wires, whereas the RS125 uses all five.
To connect the RS125 to the existing SeaTalk1 bus the connections should be made as follows:

Red & Green from the RS125 to the Red of SeaTalk1
Yellow from the RS125 to the Yellow of SeaTalk1
Brown & Bare from the RS125 to the Black/Bare of SeaTalk1

Once wired properly and energized with +12Vdc you should get a gps fix within 3 minutes, typically less than a minute, and hold that fix until gps is de-energized.
If wired and powered properly, (no loose connections, corrosion and at least 11.5Vdc) and the intermittent gps fix condition persists, then you have a bad RS125.
You should have at least software version 4.29, with the latest software being version 5.69 on your E-Series classic MFD.